Method of and system for selective wave transmission



April 22 1924. v 491,772 J. H. HAMMOND. JR

METHOD OF AND SYSTEM FOR SELECTIVE WAVE TRANSMISSION Original Filed April 26, 1? 3 Sheets-Shet 1 I V 1 WITNESSES I INVENTOR ATTORNEYS I J. H. HAMMOND. JR

METHOD OF AND SYSTEM FOR SELECTIVE WAVE TRANSMISSION April 22 1924. I 1,491,772

Original Filed April 26 1912 3 Sheets-Sheet 2.

,, imam 6 ,Hlllll WITNESSES April 22, 1924. 1,491,772

v J H. HAMMONDQ JR METHOD OF AND SYSTEM FOR SELECTIVE WAVE TRANSMISSION Original Filed April 26, 1912 3 Sheets-Sheet- ZZOLM 1 5mg E L;

.IIII

ATTORNEYS Patented Apr. 22, 1924. I

uurrso sr'rss JOHN HAYS HAMMOND, .13., or stouons'rnn, MAssAcHusE'r'rs.

METHOD OF AND SYSTEM FOR SELECTIVE WAVE TRANSMISSION.

Application filed April as, 1912, serial No. 693,380. Renewed December 21, 1918. Serial No. 267,874.

To all whom it may concern:

Be it known that I, JOHN HAYS HAM- MOND, Jr., a citizen of the United States, residing at Gloucester, in the State of Massachusetts, have invented 'crtain new and useful Improvements in Methods of and Systems for Selective Wave Transmission, of which the following is a specification.

My invention relates to improvements in methods of and systems for transmitting energy by means of electro-radiant waves,-

and relates more particularly to systems wherein selectivity in transmission is secured by employing distinctive wave lengths and distinctive wave-group frequencies.- In such systems I secure a still higher degree of selectivity by transmitting and receiving these waves and wave groups at a definite set rate by means of interrupters, located either at the transmitting or the receiving stations, as is hereinafter more fully set forth.

Fig. 1 shows, in diagrammatic form, a transmitting station capable of sending out electric waves of two different lengths or wave frequencies at two different group frequencies.

Fig. 2 shows, in diagrammatic form, a receiving station for receiving waves'of two different lengths at two difierent group fre-.

quencies, and at a definite of interrupters.

Fig. 3 shows, in diagrammatic form, a receiving station for receiving waves of two difierent lengths at two different group frequencies, and at a definite set rate by means of interrupters, but with a modified form of receiving apparatus. Fig. i shows, indiagrammatic form, a transmitting station for sending out electric waves of two different lengths at two different group frequencies, and at definite set rates by means of interrupters.

Fig. 5 shows, in diagrammatic form, a receiving station adapted to receive set rate by means waves of two different lengths at two difierent group. frequencies and at definite set rates, as transmitted from a station such as shown in Fig. 4. v

Fig. 6 shows, in diagrammatic form, a

modified form of transmitting station for only one alternating current generator in-\ stead of two.

In Fig. 1, A is an antenna grounded at E, and inductively connected, by means of the coils L and L, with the oscillatory circuits L S C and L S C respectively. G is an alternating current generator, which when the key K is closed, furnishes current of a definite frequency to the step-up transformer. T which charges condenser C L S C is an oscillatory circuit having a,

predetermined frequency of-oscillation, and which, being in resonance with the antenna circuit A L E causes the latter to radiate electric waves of a definite length at a definite group frequency. The frequency of the individual electric waves is above the range of audibility as is customary in the. case of energy radiated from an antenna. G is an alternator having a frequency different from that of G and when the key K is closed it supplies current to the step-up transformer T which, in. turn, charges condenser G L S C is an oscillatory circuit which has a vibration period different from that of L S C and which, being in resonance with -the antenna circuit A L E causes the latter .ate the receiving circuit tuned, to the receiver-interrupter frequency, it is necessary to have keys K and "K closed.

In Fig. 2, B is an. antenna, connected with the two tuned antenna circuits 'B I L C E and B I L C E through the interrupter's I and I respectively- M is a motor which' operates the interrupters I and I at a predetermined rate. As clearly Thus when keys K and K are number of teeth or projections and wherein the interrupter I is shown as closing the circnitbetween the coil L and the antenna B, whereas, the contact arranged 'to be engaged by the teeth of the interrupter I is substantially eqni-distant from adjacent teeth of the interrupter, the interrupters I and I are so arranged as to connect the coils L and L alternately or in rotational sequence with the antenna B.'

The two antenna circuits are tuned to the two oscillation frequencies, or wave lengths, of the transmitter, and are also in tune with the oscillatory circuits L C and L C, respectively. Rectifier R and coupling coil L receive oscillatory currents from the circuit L 0' through the stopping condenser D Rectifier R and coupling coil L receive oscillatory currents from the circuit L G through the stoppingcondenser D The oscillatory circuit L C L is coupled to L and is tuned to oneof the group frequencies of the transmitting station. The oscillatorycircuit L C L is coupled to L and is tuned to the other group frequency of the transmitting station. R is a rectifier and N an electro-magnet. Coil L is coupled to L, and L is coupled to L. Whenever I closes the antenna circuit B I L C E, unidirectional current impulses are induced in the untuned circuit L R L N. These current im pulses have a frequency corresponding to that of one of the group frequencies of the transmitting station, but come in sets which have a rate corresponding to that of interrupter l Whenever I closes the antenna circuit 13 I L C E unidirectional current impulses are induced in the circuit L R L N of a frequency corresponding to that of the other group frequency of the transmitting station, and in sets having a rate corresponding to that of interrupter I The tuned reed Q is responsive to the combined rate of these two sets of current impulses, and when this combined rate is of the proper value, Q is set in vibration and makes and breaks the circuit U-V, comprising the reed Q, the battery U and the telephone receiver V, and signals of a definite pitch, are heard in the telephone V. It should be noted that these signals cannot be received at V unless the corresponding;

wave length and wave group circuits at the transmitting and receiving stations are in tune with each other, and the vibrating reed Q is in tune with the combined rate of the interrupters I and I, thus making.

the system very highly, selective. With regard to the interrupter rate, it should be noted'that I and I make contact at different mauve telephone WV, coupled to the coil L of the untuned circuit L R L L.

When the combined rate of the sets of unidirectional current impulses in circuit L R L L corresponds with the period of the tuned oscillatory circuit L"' C W, currents are induced in the latter and signals are received in W.

In Fig. 4, G and G are alternating current generators of different frequencies, supplying current to transformers T and T,

and controlled by keys K and K", respectively. Condensers C" and C are charged by transformers T and T respectively, and discharge through the oscillatory circuits, C" L S and C L S. which have different periodicities. C" L S is inductively coupled, through the coil L, with the antenna circuit A, I Li E and C L S is inductively coupled, through the coil L, with the antenna circuit A I L E. A is an antenna and E a ground. I and I are interrupters, mechanically connected to, and operated by the motor M tacts of these interrupters, as shown, are so arranged as to connect first one antenna The concircuit A 1 L E and then the other antenna circuit, A l L E to the antenna AK. 'When keys K and'K are both closed,

antenna A radiates two series of electric waves of two different definite. lengths or wave frequencies at two different definite group frequencies, these wave groups being sent out in sets by the respective interrupters receiving system adaptedto be used in con- 1 nection with a transmitting system such as is shown in Fig.- 4. Such modified receiving system comprises an antenna B forming a part of the two tuned antenna circuits B2 L35 C23 E5 B2 L36 C24 E8 These two circuits are tuned to the two wave lengths of the transmitter by means of the inductance coils, L and L and the vaiiable condensers, C and. C, respectively.

Oscillatory circuit L C is tuned for resonance with antenna circuit 13 L C E, with which it is inductively coupled by means of L and L Rectifier R and coupling coil L receive oscillatory currents from circuit L 0 through the stopping condenser D.

L is tuned in resonance with one of the group frequencies of. the transmitting station, by means of the coils L and L and the variable condenser C. By means of the coupling coils L and L, circuit L C L induces alternating currents in the untuned circuit L R L L which currents, being rectified by R, act:-

as unidirectional impulses on the tuned circuit L C W c The second antenna circuit 13 L C E is inductively coupled with the oscillatory circuit L, C, with which it is in resonance. Rectifier R and coupling coil L receive oscillatory currents from L C through the stoppin condenser D. The oscillator} circuit L L is tuned to resonance with the second group frequency of the transmitting station, and, by means of the coupling coils L and L, it induces alternating currents in the untuned circuit L R L L, which currents, being rectified by R, act as unidirectional impulses on the tuned circuit L C W.

Circuit L C W com rises the coil L, the variable condenser and the telephone receiver W, and this circuit is tuned to resonance with the combined rate of the interrupters at the transmitting stat-ion.

Each time the interrupter at the'trans transmitting station closes its circuit L4,

in a similar manner to that just outlined, receives .unidirectional current impulsesat a definite rate corresponding to the second group frequency of the transmitting station, and these impulses likewise give the same effect as a single long. impulse in their action on circuit L E" W.

When the keys K and K of the transrnitting station shown 'in Fig. 4 are both closed, circuit L C 1 of Fig. 5 will receive impulses successively at rates corresponding to the frequencies of interrupters I and 1, of Fig. 4:, respectively. These interrupter rates will be combined in their influence upon circuit L C W Thus, if I and I each makes 250 contacts per second, circuit L C W will receive 500 impulsesper second, and if it is tuned to this frequency of 500, it will respond, and oscillatory currents will be induced in it which will affect the telephone receiver W.

The oscillatory circuit ci'fic wave-group frequencies, and two spe- It is evident, therefore, that in order to produce a signal in recei'ver W it is necessary to have electric waves of two definite lengths, each with its definite group frequency, and that these wave groups, moreover, must be sent out in sets, each at a definite set rate. In other words, the

receiver will respond onl to a combination of two specific wave engths, two specific group-set rates. This, therefore, secures a. remarkably high degree of selectivity. a

In Fig. 6, G is a source of'alte'rnating current connected through a key K, with a commutator H, which supplies current successively .to the primary windings of transformer, T and T, respectively. The secondary windings of T and '1 form parts of the'oscillatory circuits C S L and C S L res ctively. These oscillatory circuits are in uctively coupled to the antenna circuits A L E and A L E by means of'the coils L and L respectively. The spark aps S and 'S in the oscillatory circuits h L and (3 8 L respectively, areof difierent lengths, so that the spark frequencies (or group frequencies) of the groups of electric waves may have different values. p c The alternator G5 should have a frequenc of a higher order than that of the spar gapsgso that several alternations of current shall occur during each spark. Instead of v the alternator, there may be a direct cur- 9 rent generator or battery as a primary source of current for supplying the condensers C? and C the spark gaps S and S and the oscillatory circuits C S L and C S L? directly through the commuta- 105 tor H.

H also fills the place of the two interrupters and being operated at a definite rate, will supply sets of current waves successively to the two antenna .circuits, each of these sets of current waves being composed of wave groups of a definite frequency, and each wave group being composed of waves of a definite length. 1

This invention is not limited to the articular apparatus herein described, nor is it limited to the transmission'of'signals, since the received energy can be utilized for the selective operation of various mechanical arrangements and devices, nor is the invention' limited to any particular frequencies of waves, wave groups or group sets.

Having thus described my invention, 1 claim:- s

1. In a system of selective wave transmis,-. skin, a transmitting station having means- -for emitting a plurality of co-existing se'-' group frequencies, said wave group being emitted in sets having rates different from the wave frequencies and the wave-group frequencies.

2. In a system'of selective electric wave. transmission, a receiving apparatus having means which, by reason of appropriate sets having a predetermined set rate, and in operating receiving apparatus by combinations of sets of wave groups.

4. A method of radio communication which consists in operating receiving apparatus by means of a combination of two or more series of wave groups of different group frequencies, each series of groups consisting of waves of a definite wave length, the wave groups being received in sets at a definite rate.

5. A method of radio transmission which consists in transmitting a plurality of series of wave groups, each of such series having a predetermined group frequency and the different series consistmg of waves of different predetermined Wave lengths, these wave groups being emitted in sets having a predetermined set rate, and in operating receiving apparatus by the combined action of a plurality of series of wave groups.

6. A method of radio communication which consists in transmitting a plurality of electric waves in series of wave groups and grou sets having frequency character istics ena ling said series to be separately received, and in operating receiving apparatus by means of the combined and simultaneous action of a plurality of series of sets of wave groups. v

7. A method of wavetransmission which consists in transmitting waves of different definite wave frequencies in groups of different definite group frequencies, transmitting said groups in a lurality of coexisting series of sets of de its set frequencies, the sets of one 'of said series alternating with the sets of another of said series, and

- operating a receiving device as a result of the combined action of a plurality of said series of sets. 7

8. A method of wave transmission which comprises generating waves of predetermined wave frequencies in groups of different predeterm1ned..; group -frequencies, transmitting said groups in a plurality of coexisting series of sets of predetermined mauve set frequencies receiving said plurality of series at a receiving station by selecting the waves of the predetermined wave frequencies, selecting the groups of waves of the different predetermined ou frequencies,

selecting the plurality 0 series of sets ofent predetermined group frequencies, trans-' mitting said groups in a plurality of series of sets of predetermined set frequencies, receiving said plurality of series of sets at a receiving station by selecting different waves of the said predetermined frequencies, selecting the groups of waves of different predetermined group frequencies, combining the plurality of series of sets, and causing the operation of a device as a result of the conjoint action of a plurality of series of said sets.

10; A system of wave transmission comprising means for generating waves of predetermined frequencies, in groups of predetermined group frequencies, means for transmitting said groups in a plurality of coexisting series of sets of predetermined set frequencies, and receiving means comprising means tuned to selectively receive said waves, means tuned to respond to said predetermined group frequencies, means tuned to respond to a plurality of series of sets of the said predetermined set frequencies, and means arranged to be selectively operated as a result of the conjoint action of a plurality of said selected series of sets.

11. A system of wave transmission com prising means for generating waves of different predetermined frequencies, in groups of predetermined group frequencies, means for transmitting said groups in a plurality of coexisting series of sets of predetermined set frequencies, and receiving means comprising means tuned to selectively receive said waves, means tuned to respond to the wave groups, means tuned to respond to a plurality of-series of sets, and means arranged to be selectively operated as a result of the conjoint action of a plurality of said selected series of sets.

12. A system of wave transmission comprisingmeans for generating waves of different predetermined frequencies, in groups of different predetermined group frequencies, means for transmitting said groups in a plurality of coexisting series of sets of predetermined frequencies and receiving means comprising means tuned to selectively respond to said wave fr uencies respectively, means tuned to respon respectively to the wave groups, means tuned torespond to the plurality of series of sets, and means arranged to respond selectively to the conjoint action of said. selected plurality of series of sets.

13. A system of wave transmission comprising means for generating waves of different predetermined frequencies, in groups of different predetermined group frequencies, means for transmitting said groups in 14. In a system of selective wave trans-- mission, a transmitting station having means for emitting high frequency electrical etheric vibrations in groups, and a receiving station comprising circuits successively responsive to the frequency of the electrical etheric vibrations and the frequency of their group emission and a final responsive circuit tuned to a frequency differing from the foregoing but dependent upon their conjoint action in its functioning.

15. A receiving system for waves, comprising three cooperating elements electrically tuned respectively to three different frequencies, and a receiving device arranged to be operated as a result of the conjoint and successive action of said elements- 16. In a system of selective wave transmission, means for the transmission of'high frequency waves in two series of groups, the group frequency of one of said series being different from the group frequency of the other of said series, and a single solid movable element arranged to be moved in re sponse to the conjoint action of both of said series of groups.

17. In a system of selectivewave transmission, means for the transmission of high frequency waves in a plurality of coexisting series of groups, the group frequency of one of said series being different from the group frequency of another of said series, and an electro-mechanical device arranged to be actuated in response to the conjoint action of said series of groups.

18. A- receiving system for waves comprising a plurality of cooperating circuits tuned respectively to a plurality of Wave group frequencies, and a device arranged to be actuated in response tothe action of a plurality of said circuits.

19. A receiving 'system' for waves, comprising a plurality of cooperating elements tuned respectively to a plurality ofwave group frequencies, and a device arranged to be actuated in response to the conjoint action of a plurality of said elements.

20. A receiving system for waves, comprising a plurality of successively responsive circuits tuned respectively to a plurality of wave group frequencies, and a device arranged to be actuated in response to the conjoint action of a plurality of said circuits.

21. A receiving system for waves comprising a plurality of successively responsive elements electrically tuned respectively to a plurality of different wave group frequencies, and a device arranged to' be actuated in response to the conjoint actlon of a plurality of said elements.

22. In a system of wave transmission, the

combination with means for transmitting a plurality of series of groups ofwaves of different group period-icities, of a receiving station comprising a plurality of cooperating elements tuned to said periodicities respectively, and a device arranged to be actuated in response to the combined action of a plurality of said elements.

23. In a system of wave transmission, the combination with means for transmitting a plurality of co-existing series of groups of wavesof different group periodicities, of a receiving station comprising a plurality of cooperating successively acting elements tuned to respond to said plurality of series of groups respectively, and a device arranged to be actuated in response to the combined action of a plurality of said elements.

24. In a system of selective wave transmission, the combination with means for. generating a series of waves, of means for impressing upon said waves a series of periodic variations, arid means for receiving said waves comprising two elements tuned to respond to said waves and said variations respectively, and a third element tuned to a frequency different from the wave frequency and the periodic variation frequency but dependent in its functioning upon the conjoint action of said first-mentioned two elements.

25. In a system of selective wave transmission, the combination with means for generating a series of waves, of means for impressing upon saidv waves a series of periodicvariations, and means for receiving said waves comprising two elements tuned to respond to said waves and said variations respectively, and a ;third element tuned to a frequency different from the wave frequency and the periodic variation frequency but dependent in its functioning upon the conjoint and successive action of impressing upon said waves a series of periodic variations, and means for receiving said waves comprising two elements electrically tuned to respond to said waves and said variations respectively, and a third element electrically tuned to a frequency different from the wave frequency and the periodic variation frequency but dependent in its functioning upon the conjoint action of said first-mentioned two elements.

27. In a system of selective wave transmission, the combination with means for generating a series of waves, of means for impressing upon said waves a series of periodic variations, and means for receivmg said waves comprising two elements electrically tuned to respond to said waves and said variations respectively, and a third element electrically tuned to a frequency difi'erent from the wave frequency and the periodic variation frequency but dependent in its functioning upon the conjoint and successive action of said first-mentioned. two elements.

28. In a system of selective wave transmiss'ion, the combination with means for generating waves, of means for simultaneously impressing upon said Waves a plurality of series of periodic variations having different frequencies respectively, and means for receiving said waves comprising ele- 1 ments tuned respectively to said frequencies,

and a device arranged to be controlled as the result of the conjoint action of said elements.

29. In a system of selective wave trans mission, the combination with means for generatmg waves, of means for s1multa-' neously impressing upon said waves a plurality of series of periodic variations having difi'erent frequencies respectively, and means for receiving said waves comprising elements tuned respectively to said frequencies, and a device arran ed to be controlled as the result of the con oint and successive action of said elements.

30. A- system of wave transmission comprisingmeans for simultaneously generatmg a plurality of series of waves, means for simultaneously impressing upon each of said 'serlesof waves aseries ofperiodic variations, said variations having. different frequencies respectively, and means for receivmg said waves including a plurality of elements tunedto respond to said fre uencies respectively, and a device arrang to be controlled as a result of the conjoint action of said elements.

31. .A system 10f wave transmission, comprising means for generating a plurality of series of waves, means for simultaneously impressing upon each of said series of waves a series of periodic variations, said variations having djfi'erent frequencies respechaving selectively -receiving said waves upon ele respectively to said wave frequ mama's sult of the conjoint and successive action of said elements.

32. A system of wave transmission, comprising means for generating a plurality of series of waves, of means for simultaneously impressing upon each of said series of waves a plurality of series of eriodic variations, said variations having different frequencies respectively, and means for receiving said waves including elements tuned to respond to a plurality of said frequencies respectively.

33. .A system of wave transmission comprising means for simultaneously generating a plurality of series of waves, of means for simultaneously impressing upon each of said series of Waves a plurality of series of periodic variations, said variations having different frequencies respectively, means for receiving said waves including elements tuned to respond to a plurality of said frequencies respectively, and an element controlled by the conjoint action of said firstmentioned elements and tuned t6 respond to thecombined action of two of said series of variations. 7

34. A method of wave transmisslon which conslsts in generating -waves, lmpresslng upon said waves a plurality of series Of378- ifrlodic variations, said variations having .fere'nt frequencies respectively, selectively consists in generating waves, simultaneously impressing upon' said waves a plurality of serles of er1od1c varlations, said variat ons lfl'erent frequencies respectively,

ments tuned to said frequencies respectively, and causing the operation ,of a receiving device as a result of the conjoint and successive' action of said elements. I

36., The method of wave transmission which consists in generating a plurality "of series of waves having different frequencies respectively, simultaneously impressing upon said plurality of series ofvwaves respectivelya plurality of series of periodic variations, said variations having different frequencies respectively, receiving said plurality of series of waves upon elements tuned ies and to usingthe a .result nts.

said variation frequencies, an operation of a receiving devic o the conjoint actionof saidw el 37."'lhe meth d P smitti g energy waves having a which consists in generating a series of dpredetermined frequency,

impressing in sai series of waves a plural lty of series of periodic modifications having different frequencies respectively, selectlvely, recelvmg sa1d waves and 'variatlons,

' and controlling a receiving device as aresult of the con oint and successive action of said waves and variations.

38. A system for receiving radiant energy comprising two receiving circuits tuned to respond to periodic radiant im'pulsesof differentfrequencies respectively, both of said frequencies being substantially above audibility, and a third circuit arranged to be controlled as a result-of the conjoint action of said first-mentioned circuits and tuned to respond to'impulses having a frequency dif ferent from each of said first-mentioned frequencies. I

39; The combination with means forreceiving the ener of a series of impulses modulated at a p urality of frequencies, of

- means arranged to be controlled by the reimpulses having a frequency less thanthat first-mentioned frequencies.

ceived energy for producing a current. of, electrical impulses having a frequency corresponding to one of said first-mentioned fre uencies and means arranged to becontro ed by said current of electrical impulses for producing a current of electrical of said first-mentioned current and bearing quency less than that of said second circuit and within the range ofaudibility.

42. A carrier wave transmisslonsystem comprising means for producing a series of radio. frequency impulses having simultae neouly existent therein a plurality of series of variations of higher and lower frequencies respectively, 'said series of variations of lower frequencyxbeing within'the range of audibility, a receiving "circuit tuned to the frequency of said im ulses and a second circuit tuned to said igher variation :frequency, a rectifier interposed between said circuits, a-second rectifier-controlled by said second circuit, and an indicator circuit controlled by said second rectifier. I

43. A system for transmitting'and receiving radiant energy, comprising means for.

transmitting radiant energy in such a form -as to include two series of periodic im ulses a fixed, definite relation to another of said 40. In a selective system for. the transmission of electro-radiant energy, the com bination with transmission means arranged to emit electro-radiant oscillations having a predetermined high frequency and a plurality of series of periodic variations of different predetermined frequencies, of receivmg meansarranged to selectively receive said oscillations and said variations and to function'under the control of said oscillations and said plurality of series of variations.

41. A carrier wave transmission system comprising means for producing a series of radio fr uency impulses having simultaneously existent therein a plurality of series of variations of higher and lower frequencies res ectively, sald series of variations-of lower requencypbelng within the range of audibility, a receiving circuit tuned to the frequency'of said impulses and a second circuit tuned to said higher variation fre quency, a rectifier interposed between said circuits, a second rectifier control ed by said second circuit, and a circuit controlled by said second rectifier and tuned to ya frehaving two different predetermine frequencles respectively, two receiving elements tuned to respond to said frequencies respec tively, and a third receiving'element tuned to respond to a frequency different from either of said first-mentioned frequencies and, arranged topbe controlled as a result of the cooperative action .of said first-mentionedelements.- v

44. A system of selective energy transmissionhaving at the receiving station local circ'uits responsive to impulses of different periodicities, in combination with a common circuit coupled to each ofsaid local circuits and com rising a rectifier, and an independent clrcuit coupled to said common circuit and comprising a current detector.

45. A system of distant control comprising an aerial receiving circuit, a primary closed oscillatory circuit tuned to a predetermined frequencyand arranged to be controlled by said aerial circuit, a controlling .JOHNIIAYS HAMMOND, JR. A

Signed in the presence of SAMUEL C. Yim'rorr,

. Mama. 

